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Garmin lactate threshold estimate vs Friel test

Former Member over 8 years ago

I just performed a 30 min running time trial to determine my lactate threshold as described by Friel (and posted below for reference). At the end of the run my 735xt gave me a new lactate threshold estimate of 184 bpm and 4:44 min/km. However, using the Friel way of calculating the lactate threshold gives me 191 bpm and 4:22 min/km. These values are quite different and will affect my training zones.

My question is which one is more accurate? Both methods for calculating lactate threshold are estimates, not lab tests. I was using my triHRM, does the garmin have access to sensor data that helps it obtain a more accurate estimate than the simple Friel test?

# Friel method from http://home.trainingpeaks.com/blog/article/joe-friel-s-quick-guide-to-setting-zones
To find your LTHR do a 30-minute time trial all by yourself (no training partners and not in a race). Again, it should be done as if it was a race for the entire 30 minutes. But at 10 minutes into the test, click the lap button on your heart rate monitor. When done, look to see what your average heart rate was for the last 20 minutes. That number is an approximation of your LTHR.

0 Former Member over 8 years ago

I added the ConnectIQ data field for Strava Suffer Score and TSSHr to my ride this morning at the TSSHr value shows up in GC in teh ConnectIQ Data area, but nothing for Strava Suffer Score.

My guess is that it'll only be a matter of time.

0 Former Member over 8 years ago

In my opinion Heart Rate is quite variable depending of how stressed/tired the central nervous system is (CNS).
I tend to get higher heart rates when I am less fatigued and lower heart rates when training volume is high. This doesn't necessarily track well with how I perform.

0 timgrose over 8 years ago

In my opinion Heart Rate is quite variable depending of how stressed/tired the central nervous system is (CNS).
I tend to get higher heart rates when I am less fatigued and lower heart rates when training volume is high. This doesn't necessarily track well with how I perform.

Yes similar for me. It's a particular "problem" for all these algorithms as they do rely on max HR being accurate. However the fitter I get the harder I find it to reach the highest HRs and so VO2 Max (and hence race predictions) can appear flattering. As such I have experimented with shifting max HR down a bit when I am "fit".

0 R_Tellis over 8 years ago

I did that just last week. I'm in the peak of marathon training and my Vo2Max was pegging up around 53/54 and the race predictor was giving me ~3:01 for 26.2 miles.

I lowered my HRmax by 10 and it's now giving me Vo2Max of 51 and a 3:15 marathon time which are both still pretty unreasonable (I'm shooting for 3:40-3:45 this fall) but I'll wait to see if it changes much more over the next few weeks.

0 Former Member over 8 years ago

Thank you all for the interesting conversation.

looks like he is using the ConnectIQ data filed hrTSS

Correct. The hrTSS app is great, probably the first useful app i have seen in the ConnectIQ store. However, it relies on having an accurate LTHR set in advance, which brings me back to our original conversation...

Max heart rate will leave you feeling ill for two days (the VO2max tests I did at uni spring to mind). I know my max heart rste is 184 because that's the last recorded measurement before I fell off the treadmill semi-conscious.

I am pretty shaky when hitting a HR of 205 (can become physically ill). I imagine I could go a few beats higher in a lab, but nothing more. Thanks for the tip, I might change my max HR on my garmin to reflect this. For reference I am 30, so definetly not 220 - my age :)

In my opinion Heart Rate is quite variable depending of how stressed/tired the central nervous system is

Thanks for the tip, I will repeat the test a few times and see how variable the results are. Of course this will be confounded with my changing fitness.

And back to my original question... Does the garmin have access to any additional data when estimating the lactate threshold heart rate (LTHR)? If the garmin LTHR and pace estimates are simply based on distance, HR and time, then I will probably stick to the Friel test as its more widely used. However, if the device factors in additional information such as HRV, gradient, etc then it may be a more accurate measure.